Topic: adding foam to velocity stacks

[greenjeans]

My pops has volunteered to make me some velocity stacks for my "poor man's" CR750 replica

So, to make them a bit more friendly to the inside of the engine, we were contemplating using 2 screens
1 on the inside and 1 on the outside and fashing some foam which could then be oiled for better cleaning
in the middle....

Any idea of what type of foam we could use, that could be cut to fit the inside of a velocity stack ?
And where we might get some ?

[hymodyne]

When you find out, I'll be very interested; I have stacks on my bike with only a fine brass screen. I'd like to add at least a thin layer of foam to increase the trapping of schmutz before it can get into my carbs...

hym

[Gordon]

I just typed "velocity stacks foam" in the search field and came up with several threads on the subject. 

Not saying you shouldn't ask, but thought you might be able to benefit from the previous work of others.

[eurban]

This has been gone over before.  Installing foam will negate any performance benefits that you might get from running velocity stacks so don't do this if you are looking for performance.  If you are in it for the looks then you could probably buy a few foam lawn mower air filters at the local hardware store.  My Lawnboy mower used to use someting like a 4" x 6" x 1" foam filter block that could be cut to make a couple of velocity stack inserts.  I am also sure you could buy larger quantities of air filter foam online.

[hymodyne]

I typed the same three words into the search field and only got the three posts of this thread...

[eurban]

The regular search function seems to be a bit funkyas of late. Try going to the advanced search option first. I searched under "velocity stack" in the advanced search and came up with lots of hits.  Here's a recent one dealing with this subject
http://forums.sohc4.net/index.php?topic=31872.15

[Gordon]

I typed the same three words into the search field and only got the three posts of this thread...

That's probably because you only searched in this thread.  Try the same thing from the main page.

[dakeddie]

According to David Vizard, tuning guru for Austin Minis, putting foam in your velocity stacks will result in terrible flow... there just not enough surface area on the filtering medium.  He tested this on a flow bench.  It will surely flow worse than the stock airbox.

And screens don't do much for filtering out dust.

Velocity stacks are the ultimate in performance though, it's too bad they don't fit well inside K&N's.  If I were you, I'd put K&N's on for regular riding, and velocity stacks if you're going to show the bike.

[hymodyne]

duly corrected...

I wasn't aware that the search engine operated differently from different links...

hym

[greenjeans]

This bike is truthfully more for show than go...that's not to say that it won't be ridden.
Basically I want the "looks" of a velocity stack combined with the protection of an oiled or stock filter.
I don't really want the hassle of changing between a true velocity stack and pod filters etc.

I've looked through some past posts and found some good stuff, but I was looking mainly for a source of a foam
that could be shaped to fit inside the stack betweeen some screens... Hadn't even thought of a lawn mower filter....
That will be worth a try.  Every question has been asked before, and sometimes it doesn't always yield the same answers.  Somebody has usually already solved my problem/question and it can be easy to miss reading through post after post of similar answers...thus breading my general lazyiness on searching and searching.  I know I'm contributing to my own problem and believe me, I'm trying not to ask so many questions - but is addictiing knowing you can post a question and have a wealth of answers and knowledge in such a short time.

I'm going to give the lawn mower filter a shot & I'll post the results. 

At least I haven't asked about jetting for them

[heffay]

BAH!  if you're gonna run stacks... run em!

[sparty]

You are wasting your time and money putting foam in those stacks.  You bike will run like crap.  These engines need to breathe.  There is a good reason they don't make foam for stacks.......  it does NOT work well.  You will also foul the plugs as it will run richer.  You can mess with jetting all day and it won't make a difference.  Running like crap is running like crap.  But don't listen to us, find out for yourself.  Then we can say "Told you so".

Sparty

[mystic_1]

At least we have it easy, stacks on a CB face backwards.  A lot of harley guys run with velocity stacks that point forward, like a giant funnel for channeling dust, rocks, birds, and so forth into the carb 


mystic_1

[greenjeans]

ok...ok ..... maybe I'm a bit stubborn  - I've found a couple on here that have had success with filtering material

[Sam Green Racing]

 

[754]

Dont be a pussy.. run em open..

You already said more show than go..


 Running filters on stacks is  like taking your Mom along when you go on a date..

[hapsh]

Running filters on stacks is  like taking your Mom along when you go on a date..

 


The stock airbox has velocity stacks inside the rubber airbox boots.  Oh, oops, you can't see them, shoot.
I would do what others suggested, run the stacks without any filters, just screens.  I have known several guys over the years that used to run their bikes without any filters at all and had no problems.  Yeah, if you commute 40 miles a day on the interstate, I would think otherwise.   But just cruising around here and there I would not worry about it.  You think its a pain jetting for pods, try jetting for a chunk-o-lawnmower airfilter foam 2" thick.

[heffay]

i'd have no problem running stacks on the interstate... its around town, especially near windy construction sites or dusty parking lots and roads.

[dakeddie]

This bike is truthfully more for show than go...that's not to say that it won't be ridden.

Just run the stacks... it looks wicked.  Doesn't look bad with the oiled screen too.

[greenjeans]

That's it then....no filters just the fine mesh screen.  My commute is only 1.5 miles.

[hahnda]

I can't comment on how the bike runs with them yet.

[greenjeans]

Like 'em - where'd you find them ?

[hahnda]

Dont know. They were already on there.

I do have another set of stacks though and they use something similar to hold the screens on. In the pic its just real thin foam over the screens. I guess the key is having those round holders that go over the "bell".

[heffay]

for the sake of answering your question... 

i've heard of womens' hosiery working as a 'sort of' filter
at least better than a screen door type screen

if they were my stacks... i'd only run screen or nuthin... but you knew that.   

[Geeto67]

I have a set of old circycle V-stacks that came with filters and foam. I replaced the crumbly foam with pieces of foam from a unifilter. Works fine, never had a problem on that bike because of stacks.